The present technology generally relates to an electric power supply device, a method for supplying electric power, and a power storage device, in system interconnection.
Technologies for connecting power generation facilities that generate electricity using natural energy such as solar power generation and wind power generation to an electric power system of an electric power company are generally referred to as system interconnection. When system interconnection is performed, quality similar to that of electric power supplied by an electric power company is required. Thus, when voltage generated by solar power generation or wind power generation becomes overvoltage or undervoltage, or a frequency rises or falls, this adversely affects quality of the entire system of the power company. When these troubles are detected, the corresponding power generation facility needs to be immediately disconnected from the system. Disconnection is called parallel off. In addition, there is also known a power supply system in which generated electric power is temporarily stored in a power storage system and the electric power is supplied to a load from the power storage system.
For example, when a power failure or the like occurs, power supply is switched to a self-sustaining state in which electric power is supplied to a predetermined load from the power storage system without using a system power source.